Vacuum sizer



April 23, 1968 J. c. REIB ETAL VACUUM SIZER 2 Sheets-Sheet 1 Filed Sept.4, 1965 INVENTOES. JOHN c. Jeans. JOHN o. RUSSELL 09 7- roe-Var April23, 1968 J. c. REIB ETAL 3,378,887

VACUUM S I ZER Filed Sept. 4, 1963 2 Sheets-Sheet Fla-4.

1N vs/v foe-s. JOHN c.2510. Jomv 0. RUSSELL United States Patent M3,378,887 VACUUM SIZER John C. Reib, RD. 3, Sugar Creek Road, and JohnD. Russell, 1361 Pittsburgh Road, both of Franklin, Pa. 16323 FiledSept. 4, 1963, Ser. N 306,554

6 Claims. (CI. 18-19) This invention relates to a vacuum sizer apparatusfor forming or shaping tubing or other tubular workpieces of athermoplastic material.

For many years it has been common practice to pro duce thermoplastictubing by an extrusion molding process which process is satisfactory forproducing the tubing, but which process does not produce a tube tocommercially desired dimensions within acceptable tolerances. Thisdifficulty with extrusion processes was recognized by one inventor whoproposed to obtain acceptably dimen sioned tubes by applying a vacuumthrough a tube sizing structure to a plastically deformable tube whereinthe tube is drawn into engagement with the sizing structure. Suchprocess is known as vacuum sizing and is best described in Patent3,229,005, issued on Jan. 11, 1966. With the structure according to thatpatent the tubular shaping or sizing member is of fixed length having anelongated portion for receiving tubing from an extruder in which portionthe tubing is progressively sized and cooled. With such progressivecooling the elongated portion for receiving tubing must comprise atapered bore having a taper suitably related to the shrinkage rate ofthe tubing. This shrinkage rate varies in response to a number factorsincluding the type of material of the particular tubing being processedand the wall thickness of the tubing as well as the rate and degree ofcooling necessary to transform the particular material from aplastically deformable state to a state in which the tubing is no longerplastically deformable. With so many variables it has been foundimpracticable to form such sizing members in quantity. Accordingly, suchsizing members are supplied approximately to size with the user thenadapting such sizer to his particular operations. In practice it hasbeen necessary to machine such sizing members for each forming operationon a trial and error basis until a satisfactory forming operation couldbe achieved with the sizing member. Because of the above cited number ofvariables in volved in the forming of a particular type of tubing, thereis little likelihood that the same sizing member will be satisfactoryfor tubing of a slightly different wall thickness or type of material.For example, a sizing member which is satisfactory for a first plasticmaterial cannot normally be employed for a second plastic material whichhas a different coefiicient of thermal expansion or which is extruded ata different temperature or is being manufactured with a greater orlesser wall thickness. Thus with variation in tubing requirements orphysical characteristics it is necessary to use a different sizingmember or, if possible, resize the sizing member used for some othersizing operation. Although, in theory, it may be possible to stock asizing member for each sizing operation to be performed, such stockingis extremely costly in view of the large number of thermoplasticmaterials which are commercially employed and the large number ofcommercially desirable wall thicknesses of the tubes.

The apparatus and method of the present invention contemplate the use ofa plurality of sizing members each having a short tubing receivingportion as compared to the tubing receiving portion of the abovedescribed prior art device. The sizing members of the present inventionare axially movable relative to each other and are short enough so thatno one of the sizing members need have a tapered bore since the effectof the tapered bore can 3,378,887 Patented Apr. 23, 1968 be achieved byslight differences in diameter of the bores in the various sizingmembers and the effective rate of taper can be varied by varying theaxial separation between such sizing members. Consequently, with thedevice of the present invention the effective rate of taper can bematched to the variables existing in the partiuclar tubing being sizedwithout the necessity common to the prior art devices of remachining thesizing members or producing an entirely new sizing member.

The device of the present invention further provides for relatively easyinterchange of sizing members should it become necessary to usedifferent sizing members for tubing of a different outside diameter.

These and other objects and advantages of this invention will becomemore fully apparent upon consideration of the following description anddrawings in which:

FIGURE 1 is a side elevational view of a forming apparatus constructedin accordance with the principles of this invention with portionsthereof broken away to more clearly illustrate the structure thereof;

FIGURE 2 is an end elevational view of the apparatus as shown in FIGURE1;

FIGURE 3 is an end elevational view of one sizing member and the supporttherefor constructed in accordance with the principles of this inventionwith portions thereof broken away to more clearly illustrate thestructure thereof;

FIGURE 4 is a cross sectional view of the sizing member shown in FIGURE3 taken substantially along the line 44 thereof;

FIGURE 5 is a perspective view of the sizing member shown in FIGURE 3;

FIGURE 6 is an end elevational view similar to FIG- URE 3 of anothersizing member and] the support therefor constructed in accordance withthe principles of this invention;

FIGURE 7 is a cross sectional view of the sizing member shown in FIGURE6 taken along the line 7-7 thereof; and

FIGURE 8 is a perspective view of the sizing member shown in FIGURE 6.

Referring to FIGURES l and 2, the apparatus of this invention comprisesan open sided frame having an upper rectangular frame portion 2 whichoverlies and is spaced upwardly from a lower rectangular base 4 beingrigidly connected to the corresponding corners of the frame portion 2 bysubstantially vertically upwardly extending legs 6. As shown the frameportion 2 is slightly narrower than the base 4 so that the legs ,6 areinclined toward each other at each end of the base 4. If desiredsuitable rollers 8 are rotatably secured to the under side of the base 4at the corners thereof to permit easy movement of the entire assembly.

Each corner of the frame portion 2 has an upwardly extending tubularpost 10 rigidly secured normal to the plane of the frame portion 2 toprovide vertical guides for an upper tank 12. As shown, the tank 12comprises an upwardly open sided box structure the opposite sides ofwhich engage the inner opposed portions of the lateraly spaced pairs ofposts 10 and the ends of which are extended laterally to engage theopposed end surfaces of the longitudinally spaced pairs of posts 10.Tank 12 is vertically adjustably secured to the lower frame work bymeans of suitable adjusting screws 14 threadedly secured tolongitudinally spaced ends of the frame portion 2, respectively, andabuttingly engaging the bottom plate of the tank 12. An upwardly opentrough member 16 extends longitudinally between and is rigidly securedto the ends of the tank 12. Trough member 16 is divided intolongitudinal sections as desired by means of suitable bafiics 1S spacedintermediate the ends of the trough member 16. Battles 1-8 are securedto the length of the inner periphery of the trough 16 and are providedwith an upwardly open notch 20 to permit tubing to pass therethrough ashereinafter described. A pair of laterally spaced parallel rods 22extend longitudinally between and are rigidly secured to the ends of thetank 12 inwardly adjacent the sides of the trough 16 and upwardlyadjacent the arcuate bottom portion thereof. Rods 22 are provided forvarious sizing members which illustratively in FIGURE 1 comprise adouble function first sizing member 24 and a pair of single functionsizing members 26 and 27 hereinafter referred to as second and thirdsizing members, respectively, since the tubing element to be sizedpasses through these members in that order.

A single function sizing member 26 as shown in FIG- URES 6, 7 and 8comprises a cylindrical sizing sleeve 28 having a plurality ofcontinuous parallel grooves 30 extending radially outward from thesurface of an axial bore 31 in the sleeve 28. As shown, grooves 30 areaxially spaced from each other and located in an axially intermediateportion of the sleeve 28. The intermediate portion of the exteriorsurface of sleeve 28 is also provided with a number of circumferentiallyspaced ports 32 which extend radially inwardly from the outer surface ofthe sleeve 28 with the inner ends thereof spaced radially outwardly ofthe inner surface of the sleeve 28 by a distance somewhat less than thedepth of the grooves 30 so that the ports 32 communicate with thegrooves 3t). By providing such ports 32, pillar portions 34 are providedbetween the ports 32 and the outer surfaces thereof with the pillarportions 34 radially inwardly recessed so that the ports 32 arecircumferentially interconnected at their outer ends. The outer surfaceof the sleeve 28 axially outwardly adjacent each axially spaced side ofthe port 32 is provided with a continuous inwardly extendingcircumferential groove in which a suitable deformable O-ring 36 islocated. One outer end of the sleeve 28 is provided with an outwardlyextending annular flange 38 for a purpose to be described.

A formed generally disk shaped holder 40 has an axial bore 39 extendingtherethrough of a size to receive the sleeve 28 with the flange 38engaging one side surface of the holder 40 which has an axial dimensionsuch that the other end of the sleeve 28 is flush with the other side ofthe holder 40. Bore 39 is of a size to deform the rings 36 to preventleakage of ambient air into the ports 32 between the sleeve 28 and theholder 40. As shown, diametrically spaced portions of holder 40 areprovided with outwardly extending lugs 42 having downwardly open slots44 extending therethrough parallel to the bore 39.The diametricalspacing of the slots 44 is equal to the spacing of the rods 22 so thatthe holder 40 with sleeve 28 inserted therein may be freely instaledover the rod 22 suitably engaging the upper surface thereof and slidabletherealong as desired. The holder 40 is releasably secured to the rods22 by any suitable clamping means such as clamps 46 each of whichcomprises a pair of end plates 47 slidably receiving the rod 22 and ashort cylindrical pin 48 in suitable parallel bores in the end plates46. A central portion of the pin 48 having a diametrical threaded boretherethrough is suitably received by a suitable elliptical bore 49 (seeFIGURE 3) in the lug portion 42 with a threaded retaining element suchas cap screw 51 threadedly engaged with the pin 48 so that tightening ofthe cap screw 51 rigidly secures the slot 44 in engagement with theupper surface of the rod 22. It is to be appreciated that the clampingmeans 46 can be of any type which releasably secures engagement of thelug 42 with the rod 22.

The third sizing member 27 is entirely similar in construction to thesecond sizing member 26 having only a slightly smaller bore therethroughfor a purpose to be described. The holder 40 is provided with a suitablethreaded radial bore 52 communicating between its outer surface and theaxial bore 39 at a point aligned with one of the ports 32 so thatcommunication is established between the bore 52 and grooves 36. Thebore 52 threadedly receives a fluid conducting tubing 54 which in turncommunicates with a multiple conection header 56 suitably conected by afluid conducting connection 58 to a vacuum pump 60 driven by a suitablemotor suitably supported upon the base portion 4 and providing apressure lower than atmospheric through the connection 58, the header56, the tubing 54, the bore 52 and the ports 32 to the grooves 30 asshown in FIGURE 1. The grooves of the other single function sizingmember 27 are similarly connected by way of the header 56 with thevacuum pump 60.

The double function or first sizing member 24 has similar grooves 30 andports 32 in a generally cylindrical sleeve 68 similar to the sleeve 28excepting that it has a greater axial dimension and is provided with acontinuous peripheral groove 70 parallel to the ports 32 and axiallyspaced therefrom with one of the O-rings 36 therebetween to preventcommunication between the groove '70 and the ports 32, a third O-ring 36engaging the surface of the bore 39 in the holder 40 preventscommunication of the groove 70 with the ambient air. A suitable radialbore 72 communicates between the surface of the holder 46 and the groove70 and in turn suitably communicates through a connection 74 with amultiple outlet header 76 which is in turn connected through a suitableconection 78 to a suitable source of water under pressure to furnishwater through the connection 78, the header '76, the connection 74 andthe bore 72 to the groove 70 for cooling purposes as hereinafterdescribed. A suitable bore '73 in the bottom of the holder 40' providesmeans for draining the water from the groove 70 into the bottom of thetrough member 16 which in turn communicates through a plurality of drainconnections 77 with a drain header 79 through which water is drainedfrom the trough member 16 to a suitable place of disposal as may bedesired.

The holder 40 is in all ways similar to the holder 40 excepting only forhaving a greater axial dimension to accommodate the somewhat longersleeve 68 and is clamped upon the rods 22 in an entirely similar mannerhaving clamps 46' composed of clamp plates 47 and cylindrical pins 48somewhat longer than the pins 48 with cap screws 51 releasably securingthe holder 40' upon the rods 22 in a desired position. The header 76 isprovided with a plurality of downwardly extending connections 82 spacedalong the header 76 in desired positions and provided with nozzles 83for a purpose to be described.

A threaded element such as a jack screw 86 is threadedly engaged with alongitudinally extended portion of the frame 2 at the lefthand end ofthe apparatus as viewed in FIGURE 1 to abuttingly engage a frame portionof a puller mechanism (not shown) for the purpose of longitudinallypositioning and stabilizing the apparatus in relationship to such pullermechanism.

In operation of the device of this invention a device for continuousextrusion of plastic tubing in a self-deforming molten state ispositioned at the righthand end of the device as viewed in FIGURE 1 andaxially aligned with the sizing members 24, 26 and 27 at a distance fromthe first sizing member 24 found to be suitable for the particulartubing being produced. By techniques well known in the art a firstportion of the extruded tubing is threaded through the sizing members24, 26 and 27 in that order and attached to the pulling mechanism. Wateror other fluid cooling medium is forced upward through the connection 78into the header 76 from which it is supplied through the connection 74to the groove 70 in the double purpose first sizing member 24 from whichit drains through the bottom bore 73 into the trough member 16 andfalling by gravity through one of the drains 77 flows out of theapparatus through the drain header 79. The rate of fiow and temperatureof the water or other cooling medium is controlled so that as the tubingtravels through a first portion of the first sizing member 24 it iscooled to a plastically deformable state defined as that state in whichthe tubing may be permanently deformed without producing substantiallyresidual internal stresses therein.

The vacuum pump 60, suitably activated by the motor 30 operated bysuitable electrical controls communicating with a device supplyingelectricity in a well known manner, removes air from the connection 58and the header 56 producing a partial vacuum therein as is known. Theheader 56 communicates with the grooves 30 in the sizing members 24, 26and 27 through their respective connections 54, bores 52 and ports 32.As the tubing passes through the double purpose first sizing member 24it is first cooled as hereinabove described and then passing into theportion of the member 24 adjacent to the grooves 30 is vacuum sized toan outside diameter equal to the diameter of the bore in the sleeve 68under the influence of the pressure differential existing between theinterior of the tubing which is at atmospheric pressure and the exteriorof the tubing at a relative low pressure induced by the vacuum pumpconnected to the grooves 30 as hereinbefore described. As the tubingleaves the double purpose first sizing member 24 itis still plasticallydeformable until further cooled by a stream of water from one of thenozzles 83 supplied with pressurized cooling fluid such as water fromthe header 76 through the connection 82. As the tubing progresses fromthe sizing member 24 to the second sizing member 26 it is cooled by thefluid from the nozzle 83 and becomes somewhat smaller in diameter due tothermal contraction. Since some unbalanced forces such as gravity and astretching force due to the pulling mechanism are being applied to thetubing at this time the cross sectional profile of the tubing may varyfrom the desired shape as for instance out of roundncss or eccentricityof a desirably round tubing.

Further finishing is necessary to restore the desired cross sectionalprofile and this is accomplished in the second sizing member 26 whichhas a bore slightly smaller in diameter (probably only a few thousandthsof an inch) and is therefore suitable to restore the desired crosssectional profile and apply further surface finishing to the tubingwhich is now cooled to a point where it is only slightly plasticallydeformable. After passing through the second sizing member the tubing isexposed to spray from one or more of the nozzles or to a current of gasin the case a gaseous cooling medium is being used and after beingfurther cooled and as a result further contracted enters the thirdsizing member 27 where further surface finishing and restoration of thedesired cross sectional profile is accomplished in the same manner.Exiting from the sizing member 27 the tubing passes out of the device ofthis invention through the puller mechanism.

It is to be appreciated that the principles of this invention can beapplied to the use of two sizing members as well as to the use of three,four or more sizing members in that the advantages of this inventionreside in the axial movability of the different sizing members inrelation to each other so that if a tubing having a different shrinkagerate, i.e., being made of a different plastic material or having adifferent wall thickness, is to be produced the different sizing memberscan be given a different spacing which has the effect of applying adifferent taper to match the changed shrinkage rate.

It is to be noted that should it become necessary to change one or moreof the sizing members such change is easy to accomplish with the deviceof this invention since it involves only the loosening of two cap screwsand the disconnecting of the fluid connections for removal of any one ofthe sizing members.

A preferred embodiment of the present invention having herein beenillustrated and described, it is to be realized that variations thereincan be made without departing from the broad scope of this invention. Itis accordingly respectfully requested that this invention be inter- 6preted as broadly as possible and limited only by the prior art.

We claim:

1. A vacuum sizer comprising, a housing member having a through bore, anopen ended sizing sleeve member located within said bore having axiallyspaced outer surface portions cooperable with spaced surface portions ofsaid housing member to provide air seal regions, one of said membershaving intermediate said spaced surface portions thereon, acircumferential chamber extending inwardly thereof, externallyaccessible passageway means in at least one of said memberscommunicating with said chamber, said sleeve having at least one portextending inwardly thereof and in communication with said chamber, saidport having the inner end thereof spaced outwardly from the innersurface of said sleeve, and said sleeve having at least one continuouscircumferential groove extending from the inner surface thereof and incommunication with said inner ends of said port.

2. A vacuum sizer comprising, a housing member having a through bore, anopen ended sizing sleeve member located within said bore having axiallyspaced outer surface portions cooperable with spaced surface portions ofsaid housing member to provide air seal regions, one of said membershaving intermediate said spaced surface portions thereon acircumferential chamber extending inwardly thereof, externallyaccessible passageway means in at least one of said memberscommunicating with said chamber, said sleeve having at least one portextending inwardly thereof and in communication with said chamher, saidport having the inner end thereof spaced outwardly from the innersurface of said sleeve, and said sleeve having a plurality of continuouscircumferential grooves extending from the inner surface thereof and incommunication with said inner end of said port.

3. A vacuum sizer comprising, a housing member having a through bore, anopen ended sizing sleeve member located within said bore having axiallyspaced outer surface portions cooperable with spaced surface portions ofsaid housing member to provide air seal regions, one of said membershaving intermediate said spaced surface portions thereon, acircumferential chamber extending inwardly thereof, externallyaccessible passageway means in at least one of said memberscommunicating with said chamber, said sleeve having at least one portextending inwardly thereof and in communication with said chamber, saidport having the inner end thereof spaced outwardly from the innersurface of said sleeve, said sleeve having at least one continuouscircumferential groove extending from the inner surface thereof and incommunication with said inner end of said port, a second chamberextending inwardly of one of said members intermeidate said spacedsurface portions, and passageway means in at least one of said membersconnected to said second chamber to provide egress and exit for acooling medium.

4. A vacuum sizer comprising, a housing member having a through bore, anopen ended sizing sleeve member located within said bore having axiallyspaced outer surface portions cooperable with spaced surface portions ofsaid housing member to provide air seal regions, said sleeve having acircumferential chamber intermediate said surface portions thereon whichchamber extends inwardly from the outer surface of said sleeve,externally accessible passageway means in at least one of said memberscommunicating with said chamber, said sleeve having circumferentiallyspaced ports extending inwardly from chamber and in communication withsaid chamber, said ports having the inner-ends thereof spaced outwardlyfrom the inner surface of said sleeve, and said sleeve having at leastone continuous circumferentail groove extending from the inner surfacethereof and in communication with said inner ends of said ports.

5. A vacuum sizer comprising, a housing member having a through bore, anopen ended sizing sleeve member located within said bore having axiallyspaced outer surface portions cooper-able with spaced surface portionsof said housing member to provide air seal regions, said sleeve having acontinuous circumferential chamber intermediate said surface portionsthereon which chamber extends inwardly from the outer surface of saidsleeve, externally accessible passageway means in at least one of saidmembers communicating with said chamber, said sleeve havingcircumferentially spaced ports extending inwardly from chamber and incommunication with said chamber, said ports having the inner endsthereof spaced outwardly from the inner surface of said sleeve, and saidsleeve having a plurality of axially spaced continuous circumferentialgrooves extending from the inner surface thereof and in communicationwith said inner ends of said ports.

6. A vacuum sizer comprising, a housing member having a through bore, anopen ended sizing sleeve member located within said bore having axiallyspaced outer surface portions cooperable with spaced surface portions ofsaid housing member to provide air seal regions, said sleeve having acontinuous circumferential chamber intermediate said surface portionsthereon which chamber extends inwardly from the outer surface of saidsleeve, externally accessible passageway means in at least one of saidmembers communicating with said chamber, said 8 sleeve havingcircumferentially spaced ports extending inwardly from chamber and incommunication with said chamber, said ports having the inner endsthereof spaced outwardly from the inner surface of said sleeve, saidsleeve having a plurality of axially spaced continuous circumferentialgrooves extending from the inner surface thereof and in communicationwith said inner ends of said ports, on a second chamber extendinginwardly of said sleeve intermediate said spaced surface portions, andpassageway means in one of said members connected to said second chamberto provide egress and exit for a cooling medium.

References Cited UNITED STATES PATENTS 3,169,272 2/1965 Maxson 264-2093,182,108 4/1965 Branscurn 1814 3,213,165 10/1965 Pollock 26495 FOREIGNPATENTS 780,900 8/1957 Great Britain. 880,391 10/1961 Great Britain.

ALEXANDER H. BRODMERKEL, Primary Examiner.

5 J. H. WOO, F. S. WHISENHUNT, Assistant Examiners.

1. A VACUUM SIZER COMPRISING, A HOUSING MEMBER HAVING A THROUGH BORE, ANOPEN ENDED SIZING SLEEVE MEMBER LOCATED WITHIN SAID BORE HAVING AXIALLYSPACED OUTER SURFACE PORTIONS COOPERABLE WITH SPACED SURFACE PORTIONS OFSAID HOUSING MEMBER TO PROVIDE AIR SEAL REGIONS, ONE OF SAID MEMBERSHAVING INTERMEDIATE SAID SPACED SURFACE PORTIONS THEREON, ACIRCUMFERENTIAL CHAMBER EXTENDING INWARDLY THEREOF, EXTERNALLYACCESSIBLE PASSAGEWAY MEANS IN AT LEAST ONE OF SAID MEMBERSCOMMUNICATING WITH SAID CHAMBER, SAID SLEEVE HAVING AT LEAST ONE PORTEXTENDING INWARDLY THEREOF AND IN COMMUNICATION WITH SAID CHAMBER, SAIDPORT HAVING THE INNER END THEREOF SPACED OUTWARDLY FROM THE INNERSURFACE OF SAID SLEEVE, AND SAID SLEEVE HAVING AT LEAST ONE CONTINUOUSCIRCUMFERENTIAL GROOVE EXTENDING FROM THE INNER SURFACE THEREOF AND INCOMMUNICATION WITH SAID INNER ENDS OF SAID PORT.